1. Field of the Invention
The present invention relates to a liquid crystal display on which a drive circuit and a pixel part are integrally formed on a common insulating substrate. Especially, the present invention relates to the liquid crystal display in which a plurality of one bit memories are provided to store image data for each pixel.
2. Related Background Art
A display apparatus in which a memory is provided for each pixel to store image data has been proposed. For example, a display apparatus for holding the pixel voltage by a capacitor in the memory has been disclosed in Japanese Laid Open H9-258168. A display apparatus which holds data (voltage) for designating whether or not to turn on the pixel to the capacitor in the pixel, thereby continuing still image without driving the signal lines for a prescribed period is disclosed in Japanese Laid Open 2001-306038.
If the pixel data is stored in the memory, when the screen is not rewritten, it is possible to perform display by reading out data stored in the memory. Because of this, it is unnecessary to operate a latch circuit, a D/A converter, an analog buffer and so on in the signal drive circuit, thereby reducing power consumption.
However, if the memory is provided for each pixel, when moving image is displayed, contents of the memory has to be often updated, thereby increasing power consumption. Because the memory is formed below an opposite electrode and a pixel electrode, the capacitor in the memory causes a capacitance coupling between the opposite electrode and the pixel electrode. Therefore, a voltage at both ends of the capacitor is subjected to the influence of voltage fluctuation of the opposite electrode and the pixel electrode.
FIG. 28 is a diagram schematically showing positioning relationships between the opposite electrode COM and the pixel electrode Pix, and between the electrodes at both ends of the capacitor C composing of the memory. As shown in FIG. 28, when the potential of the opposite electrode fluctuates, the potential of the pixel electrode also fluctuates by the influence, and accordingly, the potential at the upper side electrode of the capacitor composing the memory also fluctuates.
When the potential at the upper electrode of the capacitor fluctuates, the logic held to the capacitor changes, thereby causing the change of color. That is, undesired problem such as irregular color may occur.